This invention relates to a material transfer apparatus of hollow fiber type, and more particularly to a medical material transfer apparatus of hollow fiber type such as a dialyzer or oxygenator.
Hollow fiber type material transfer apparatus are well known in the art. One known dialyzer includes a tubular housing and a bundle of a plurality of hollow fibers axially extending through the housing and each presenting a material exchange membrane. A dialysate chamber is defined by the outer surface of the hollow fibers and the inner surface of the housing, a dialysate inlet and a dialysate outlet are both in fluid communication with the dialysate chamber. Partitions support the opposite ends of the hollow fibers and isolate the fiber end from the dialysate chamber. A blood inlet and a blood outlet are both in fluid communication with the interior space of the hollow fibers.
Hollow fiber oxygenators are shown in U.S. Pat. Nos. 4,239,729 and 4,376,095. Such a hollow fiber oxygenator includes a tubular housing and a bundle of a plurality of hollow fibers axially extending through the housing and each presenting an oxygen permeable membrane. An oxygen or blood chamber is defined by the outer surface of the hollow fibers and the inner surface of the housing, an oxygen or blood inlet and an oxygen or blood outlet are both in fluid communication with the oxygen or blood chamber. Partitions support the opposite ends of the hollow fibers and isolate the fiber end from the oxygen or blood chamber. A blood or oxygen inlet and a blood or oxygen outlet are both in fluid communication with the interior space of the hollow fibers.
In these material transfer apparatus of hollow fiber type, a flowpath forming member in the form of a header provides a fluid inlet or outlet for passing a material transfer fluid into and out of the fiber interior space. The term material transfer fluid used herein includes both a fluid to be treated and a treating fluid between which a certain material is transferred. The headers are fixedly secured to the opposite ends of the housing.
Prior art headers are generally provided with various sealing structures for preventing fluid leakage from the housing as shown in FIGS. 4 to 6. The sealing structures and their drawbacks are described below.
Referring to FIG. 4, the header includes three elements, a flowpath forming member 20 having a fluid inlet 200, an attachment cover 30, and an O-ring 35. When the attachment cover 30 is threadably engaged and fastened to one end of the housing 1, the O-ring 35 is secured in pressure contact to a partition 40 to provide a fluid-tight seal between the flowpath forming member 20 and the partition 40. The flowpath forming member 20 at the inner surface is formed with an annular groove to receive the O-ring 35 therein preventing movement of the O-ring.
However, blood often leaked at the joint between the flowpath forming member 20 and the partition 40 when the O-ring was not properly set in the groove or when once set-in O-ring came out of the groove during the assembly. Further, since the header included three elements, the material cost was high and the production process was complicated.
FIG. 5, illustrates a header of a one-piece member. the flowpath forming member 20 has an attachment portion 204 threaded at its flared end. When this attachment portion 204 is threadably engaged and fastened to the end of the housing 1, a tongue 206 on the inner surface of the flowpath forming member 20 is brought in pressure contact to the partition 40 to provide a primary seal. A sealant 37 is then potted through a gate 208 into a gap where it is cured to provide a secondary seal.
In this header, it is the tongue 206 in biting engagement with the partition 40 that provides a fluid-tight seal between the flowpath forming member 20 and the partition 40. However, if this seal is insufficient, the subsequently introduced sealand could flow beyond the tongue 206 over the central portion of the partition 40 to block the hollow fibers. Further, this system required a step of potting a sealant which took a quite long time until curing.
FIG. 6, illustrates another header which is similar to the previously described header shown in FIG. 4 except that the thread attachment portion 204 is continuously formed at an end of the flowpath forming member 20. The O-ring 35 is retained to provide a fluid tight seal. Although less elements are used than in the header of FIG. 4, the header of FIG. 6 had similar drawbacks as pointed out for the header for FIG. 4.